All references cited in this specification, and their references, are incorporated by reference herein in their entirety where appropriate for teachings of additional or alternative details, features, and/or technical background.
Disclosed in the embodiments herein is an improved process related in general to immersion coating of electrostatographic imaging drums, and more particularly, to compressible plugs for prevention of leakage of coating solution inside such a drum. Moreover, the new plug allows use of a universal chuck connected to a carrier for transporting the drum through the coating and drying process.
Electrophotographic imaging members are known. Electrophotographic imaging members include photosensitive members, known as photoreceptors. Photosensitive members commonly utilized in electrophotographic (xerographic) processes may comprise, for example, a flexible belt or a structure such as a rigid drum.
Rigid electrophotographic imaging members, including drums, may be coated by many different techniques such as spraying coating or immersion or dip coating. Dip coating is a coating method typically involving dipping a substrate in a coating solution and taking up the substrate for the drying step. In dip coating, the coating thickness depends on the concentration of the coating material and the take-up speed, i.e., the speed of the substrate being lifted from the surface of the coating solution. It is known that the coating thickness generally increases with the coating material concentration and with the take-up speed.
One method for dip coating electrophotographic cylinders or drums comprises obtaining a drum having an outer surface to be coated, an inner surface wall defining a void, and an upper opening end and a lower opening end in communication with the void, immersing the drum in a flowing liquid coating material while maintaining the axis of the drum in a vertical orientation, maintaining the outer surface of the drum in a concentric relationship with the vertical interior wall of the cylindrical coating vessel while the drum is immersed in the coating material, the outer surface of the drum being radially spaced from the vertical interior wall of the cylindrical coating vessel, maintaining laminar flow motion of the coating material as it passes between the outer surface of the drum and the vertical interior wall of the vessel, and withdrawing the drum from the coating vessel.
An electrophotographic receptor drum may have the form of a relatively narrow cylinder or tube. As coating of only the outside of a photoreceptor drum may be desired, in particular to avoid loss of the coating solution, a plug may be affixed at the top end of an electrophotographic drum before the immersion into the coating substance to prevent the coating substance from entering the void due to positive air pressure therein. A chuck member may be relied upon both to seal the top of the photoreceptor drum to prevent fluid from entering the opening in the drum by displacing air in the opening (i.e., the chuck member acting as a plug) and also carry it through this entire operation. The chuck may have a seamless plug shape to prevent the coating solutions from penetrating inside the drum by air leaking along the seam. The chuck device may be configured to have a stem portion anchored in the plug portion. The plug portion is inserted in the open top end of the photoreceptor drum to connect it firmly to a carrier assembly for transporting the photoreceptor through the coating and drying operation.
In one process, an air cylinder is used to compress a spring-loaded shaft. The shaft is extended in a downward motion. This motion stretches a sealing bladder chuck. The stretching decreases the outside diameter of the bladder. Thinning of the bladder allows the substrate, i.e. the photoreceptor drum, to be lifted into position against a horizontal shoulder. The placement against the shoulder ensures that the drum is at a nearly perfect vertical position. Once in position the air cylinder is lifted up and the bladder is forced to compress by the spring-loaded shaft. This expansion secures the photoreceptor to the carrier for the duration of the coating process. The air pressure inside the cylinder is intended to counter the penetration flow of the coating solution. Unchucking is simply the reverse operation.
The use of a single rubber bladder for sealing the drum and for moving the drum from one process step to another has worked very well over the years but has the disadvantage of not allowing different diameters of photoreceptors to be coated using a single chuck. In fact, the solid or inflatable chuck system requires a specifically fitted single chuck for each of the different size diameter drums. As a consequence, multiple diameter photoreceptors cannot be treated and transported through the same installation. As part of the task of coating different diameter photoreceptors, a plant operation requires that the individual chucks must be continually exchanged or “changed out”, commensurate with the size and number of the different photoreceptor tubes. This complicated aspect of the operation of the coating/drying process can be very time-consuming as well as adding to the cost of such a facility by the requirement of a great number of differently sized chucks.
There is a labor cost in changing chucks from one diameter to the next. There is also a material loss expected in changing out chucks due to incorrectly installed chucks resulting in the simultaneous loss of several photoreceptor drums and down time required for repair and recovery. In the prior art, there is also known special sound-absorbing members, intended purely for acting as silencers, that are inserted into a drum to reduce sound that may be caused by a drum. The incorporation of silencers adds additional manufacturing costs. Thus there is a disadvantage of using a sealing chuck assembly that fits only one specific size diameter photoreceptor drum.